I joined this forum just to post the solution to this problem; a solution that works so well everyone should know about it. The post above correctly identifies the culprit as bacteria named serratia marcescens, but does not give this wonderful, bleach-fumes-free, easy, permanent solution for getting rid of it. I found many inquiries about how to clean off this common problem, but only found the answer in one place, which is why I'm spreading the news around.
Some key words to help people find this page: pink orange deposit growth mold bacteria shower tub grout serratia marcescens prevent rid.
This works so well it is effectively MAGIC and deserves the widest possible dissemination. I'd been cleaning off this slimy stuff for fifty years and assumed it was in the water and left a deposit when it evaporated, like hard water calcium deposits. That is wrong. It is a harmless little beast once thought so benign it was intentionally injected into aquifers to trace the flow of water underground. It eats the fats in bar soap, so step one is to rinse out your shower each time you use it.
If serratia marcescens eats bar soap, it would appear to make sense to throw the soap out in the back forty and switch to body wash, which I read is made from petroleum, but I found it is not necessary. We inadvertently bought some Sam's Club Members Mark "Moisturizing Body Wash With Shea Butter" and only recently found shea butter is a fat, yet and our problems are gone! So I suspect you could still use bar soap if you rinse and spray every time.
Despite our mistake, we have not a trace of anything in our shower after two months, not even dirt, and I haven't cleaned it once, yet it looks clean as a whistle. Normally it would at least have dingy stuff where we stand that would have to be scoured off, and sometimes the orange and black bacteria and mold. Ever since the first days of using the spray, the tile and grout have looked brand new. Not only are the beasts are gone, but so is the dirt! I attribute this astonishing lack of grime to the vinegar, which I learned from my research is a terrific cleaner of almost anything.
As to the magic spray, let me give credit where credit is due. I did not come up with this formula, I only modified it to improve it based on more research and two months of experience. It was originally posted on this forum by a member named jadnashua. I used that info and added what I found during two months of experience and extensive searching elsewhere.
Jadnashua said you have to start with a clean shower, so scrub everything thoroughly one last time.
He also said to apply it liberally to a dry shower, but I have found it works fine sprayed on immediately after showering and I don't spray much. I rinse first with a handheld sprayer we already had, then spray enough magic stuff to lightly mist everything. I only rinse and spray where tiles stay wet a long time, from 18" down incl the tile floor, then walk away. Hydrogen peroxide used to be used to bleach hair blonde, so we substituted a white rug outside the shower door and we keep our towels away from it.
The original poster did not say how often we should spray. I have been spraying every day since it takes less time than drying the shower. Rinse, spray, walk away.
Hydrogen peroxide is part of the formula. It is water with an extra oxygen molecule, making its formula H2O2. It hates sunlight, air, physical contact with other substances and even sitting unopened on a shelf, all of which make it lose its extra oxygen molecule. That turns it into H2O, plain water; useless for our purposes. For that reason, I make up the solution without hydrogen peroxide, adding it only when I fill my handheld Walmart spray bottle. A sprayer full lasts at least a couple weeks. H2O2 will be plain water a month after opening it, and after about six months unopened on the shelf.
BUY THE FOLLOWING:
1. One HALF gallon of the cheapest vinegar you can find.
2. Boric acid. You will need one cup for the first batch. Boric acid is a powder and for many years was dusted around the house to kill roaches, but it is one of the safest chemicals there are for humans, so no precautions are necessary. You will find boric acid ($3 in July, 2017) in Walmart sold as Enoz Roach Away. It comes in a bright yellow, 16 oz. by weight, plastic bottle that holds two cups. My Walmart stocks it in two locations: Insecticides, where it was sold out, and Food, which was not.
3: A quart or two (but no more because it goes bad) of hydrogen peroxide. In July of 2017 it was 88 cents a quart in the Walmart pharmacy First Aid section. It is sold in dark plastic bottles to protect it from light, it must be used within a month after opening and it must be recapped tightly.
4: An excellent 88-cent Walmart clear plastic empty 32 oz spray bottle with volume marks in ounces and mL. Mark it SHAKE WELL with a Sharpy.
5. Find a spare one gallon jug, rinse it and label it SHAKE WELL.
DIRECTIONS FOR MIXING
In the gallon jug, add one half gallon of vinegar and funnel in one cup of boric acid. Shake well. Not all the boric acid will dissolve. You now have half of your magic mixture. You will make the complete mixture in the spray bottle as required. To fill your sprayer, shake your gallon jug and fill the sprayer half full with the vinegar boric acid mixture. Without touching the mouth of the hydrogen peroxide bottle to the sprayer, fill the rest of it with H2O2. Shake. The spray will leave a barely visible white coating of boric acid after it dries.
The hydrogen peroxide is an odor free bleach substitute. It and the vinegar strip the cell walls from the S. marcescens and the boric acid keeps it from coming back.